The present invention relates to surgical instrument and more particularly to an aorta punch for use in saphenous vein grafts, and the like.
In cardiac surgery, saphenous vein grafts are used to bypass diseased areas of the coronary arteries, and the present invention is used in the preparation of an opening in the ascending aorta where the proximal end of the saphenous vein may be anastomosed. In the past, incisions in the aorta were made with surgical scalpels or scissors or combinations of these with the shape varying from widened slits to triangular. It has also been suggested to use various punches in an attempt to provide an accurate, clean circular opening. The function of such a punch depends on the introduction of a support, or anvil into the aorta or artery through an incision in the arterial wall. Using one hand, the thumb and opposed first and second fingers are approximated to pull a cross-bar which pulls down a tubular cutting device which pushes the aortic wall against an anvil in the lumen. Great pressure has to be exerted in order to accomplish the desired result. Such a system has proved unsatisfactory because of the great pressure required by a blade pushing against an anvil. Accordingly, it is one purpose of the present invention to overcome the disadvantages mentioned and to provide a cutting mechanism with a shearing, or scissor-like action. This is accomplished by allowing the portion of the shearing punch which is introduced into the vessel lumen to share in the cutting action as a fixed blade which slides into the cutting blade to "punch" an opening. Pressure is maintained on the instrument until the "plug" has been removed in order to avoid leaving any residue in the aorta which could constitute an embolus. The side of the fixed blade which opposes the circular cutter is hollow ground to facilitate the cutting action. To achieve an ideal opening, especially since the presence of adventitia in the area readily binds the cutting mechanism, demands a razor-like cutting edge and a very close tolerance between the two shearing edges, the instrument has to be manufactured as a precision instrument with disposable cutting blades.